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Physio Lab Exam 1
| Question | Answer |
|---|---|
| A _______ ______ contraction is when your muscle fibers lengthen as they are actively contracting while the angle of the joint increases. | eccentric isotonic |
| Which of the following best describes a motor unit? | A single motor neuron and all the muscle fibers that it innervates. |
| Which statement about muscle contractions is true? | The tension generated by a muscle can be varied by controlling how many of its motor units are active |
| What is the term given to summation of frequent muscle twitches to give maximum contraction? | Tetanus |
| In skeletal muscle, what is a minimum unit of contraction caused by a single action potential called? | Twitch |
| When performing the knee-jerk reflex, the Jendrassik maneuver resulted in a higher kick. This was evident in the data in that: | The compound muscle potential on the EMG trace had a greater amplitude than it did without the maneuver. |
| True or False: The pupillary reflex is a monosynaptic reflex arc. | False |
| Which of the following is true? | Reflexes have fewer neurons and synapses than reactions, leading to a shorter summed synaptic delay. |
| Which of the following treatments produced the longest reaction time? | Random visual + auditory cues |
| What did the current from the stimulator bar directly stimulate when you performed the conduction velocity experiment? | The axons of the median nerve at the level of the arm. |
| In skeletal muscle, which of the following processes is ATP not generated through? | Lactic acid metabolism |
| The action potential causes the release of calcium ions from the ________ ________ in the muscle cell. | sarcoplasmic reticulum |
| Which of the following statements regarding acetylcholine at the neuromuscular junction is true? | It is broken down by acetylcholinesterase. |
| Which of the following factors have been suggested as contributing to muscle fatigue? | - Loss of "central drive". - Reduction in calcium release in excitation-contraction coupling. - Reduction in muscle blood flow owing to compression of blood vessels. -All of the above (CORRECT) |
| What does an EMG record? | Electrical activity of the motor nerves supplying the muscle fibers. |
| The electrical current from the bar electrode directly caused action potentials to be created in a/the: | Nerve of the hand |
| What is the primary neurotransmitter released at the neuromuscular junction? | Acetylcholine |
| A smooth contraction many times stronger than a single twitch is called what? | Summation |
| Which statement is true of summation in a muscle cell when a motor neuron is repeatedly stimulated with a supra-maximal stimulus current? | A second stimulus that is delivered before the muscle has had time to relax (i.e., before cell Ca2+ concentration has been restored to resting values) results in a stronger contraction. |
| You stimulated the ulnar nerve at the level of the elbow & wrist. Then measured the latency to the onset of the contraction of the hand muscles for each. By taking the difference in the times divided by the distance between the elbow and wrist of your vol | Conduction velocity |
| Nervous system | Central - brain & spinal cord Peripheral - Sensory & motor neurons |
| Peripheral - Sensory & motor neurons | Somatic nervous system Autonomic nervous system |
| Somatic nervous system | information from the periphery travels to the central nervous system (CNS) along afferent sensory nerves, and responses travel directly to skeletal muscles along effector motor nerves motor to skeleton (efferent) sensory from sense organs (afferent) |
| Autonomic nervous system | Information from the CNS travels to smooth muscles, cardiac muscles, and glands along a two-neuron efferent pathway motor to smooth muscle (efferent) sensory from internal receptors (afferent) |
| CNS | brain spinal cord brainstem |
| PNS | 31 pairs of spinal nerves motor neurons sensory neurons ganglion |
| The somatic nervous system is also known as the | voluntary nervous system |
| The autonomic nervous system is also known as the | involuntary nervous system |
| True | All action potentials are the same size An action potential will always fire once the threshold is met |
| Refer to the numbered stages in the image above. At which stages do the channels open and close during an action potential? | Stimulus-gated ion channels open voltage gated Na+ channels open voltage gated K+ channels open Voltage gated Na+ channels close Voltage gated K+ channels close |
| Unmyelinated axon | - lower membrane resistance - regeneration occurs continuously along the axon - slow conduction velocity |
| Myelinated axon | - less electrical current lost across the membrane - fast conduction velocity - saltatory conduction - high membrane resistance -regeneration occurs at the nodes of Ranvier |
| Statements regarding RMP | - the cell interior is more negative than the cell exterior - Na+ / K+ maintains an uneven distribution of cations across the membrane |
| Peripheral nerves | |
| What increases during a breath-hold? | arterial CO2 concentration blood pressure |
| What decreases during a breath-hold? | diameter of peripheral blood vessels arterial O2 concentration heart rate |
| Our arteries have chemoreceptors that are sensitive to both O2 and CO2. Are these chemoreceptors responsible for the break point? | No Urge to breathe is experienced before the actual break point is reached |
| Breath-hold duration can be shortened or extended by a number of factors. How do these factors shorten breath-hold duration? | increased metabolic rate |
| Breath-hold duration can be shortened or extended by a number of factors. How do these factors lengthen breath-hold duration? | - increased lung inflation - hyperventilation to lower arterial CO2 prior to breath hold - breathing hyperoxic (high O2 concentration) gas mixtures |
| What control centers do chemoreceptors send signals to when stimulated? | Respiratory center and vasomotor area of the cardiovascular center. |
| Stimulation of chemoreceptors causes peripheral vasoconstriction, splenic contraction, and an increased drive to breathe. What happens during peripheral vasoconstriction? | Peripheral vasoconstriction redirects blood & O2 to vital organs which conserve O2 during breath-hold |
| Stimulation of chemoreceptors causes peripheral vasoconstriction, splenic contraction, and an increased drive to breathe. What happens during increased drive to breathe? | Stimulation of chemoreceptors increases the drive to breathe to replenish O2 in the blood, and remove CO2 f.rom the body. |
| Stimulation of chemoreceptors causes peripheral vasoconstriction, splenic contraction, and an increased drive to breathe. What happens during splenic contraction? | Splenic contraction increases the O2 carrying capacity of the blood through release of RBCs. |
| What are the benefits of peripheral vasoconstriction during a dive? | - ^ perfusion of the lungs, allows ^ O2 uptake & increased pressure in the alveoli. - ^ the proportion of O2 in the blood that is available for vital organs such as the heart and brain. - reduces heat loss to the environment & maintains body temp |
| For each condition listed below, what would be the expected change in leg diameter? | Normal breathing - large change in leg diameter Breath holding - smaller change Diving - smallest change |
| What are the benefits of increased hematocrit during a dive? | Allows faster recovery from dives. Increases ability to hold breath for longer on subsequent dives. Increases O2 available for the brain and heart & transport in the blood. |
| Which of the following is thought to be the most important determinant for break point? | Ability to maintain contraction of the diaphragm. |
| Arterial O2 and CO2 pressures help to drive the desire to breathe. Whare are the false statements? | Arterial PO2 and PCO2 are the most important determinants of break point. As the PO2 increases, or as PCO2 decreases, the desire to breathe increases. |
| Which statement is true during a breath-hold? | The lung volumes decrease as more O2 is lost from the lungs than CO2 is added from the peripheral tissues. |
| What does the term bradycardia refer to? | A decrease in heart rate. |
| What is the greatest benefit of the diving response in adult humans and other land animals? | Conservation of body heat. |
| Which of the following factors best describes what would occur with reduced blood flow to the extremities? | More blood is available for the heart and brain, and increased stroke volume of the heart. |
| Which of the following responses characterizes the diving response? | Decrease in heart rate. |
| What happens to the trigeminal nerve receptor stimulation if the water temperature decreases while the face is submerged? | Stimulation is enhanced and the severity of bradycardia increases. |
| Effector | Respiratory muscles Bradycardia Heart |
| Response | Apnea Vasoconstriction Redirects blood to brain and heart |
| Function | prevents aspiration of water arterioles (skin, limbs, intestines) preserves body heat reduces O2 consumption |
| Describe any changes in pulse amplitude you observed during the simulated dive. Explain why these changes occurred. | See a consistent decrease in amplitude throughout the dive. |
| How long did the diving response take to occur? How quickly did the heart rate return to normal after a dive? | the pulse rate should have decreased in both experiments but diving should have has a more profound decrease in pulse rate |
| Which of the following statements best describes what would occur with peripheral vasoconstriction in the absence of any blood loss? | More blood is available for the heart and brain, and increased stroke volume of the heart. |
| Reflexes can be classified as | innate (generally determined) acquired (learned) spinal (process in spinal cord) cranial (process in brain) mono /polysynaptic somatic (control skeletal muscle contractions) visceral (smooth & cardiac glands) |
| Reflexes classified by | development response processing site complexity of circuit |
| Typical reflex arc | Stimulus activation of sensory neuron information processing in CNS activation of motor neuron response by effector |
| isotonic contractions | when muscles shorten causing movement (weight lifting, running, swimming) |
| isometric contractions | when muscles tension increases without actually shortening (pushing a wall) |
| Concentric | muscles shorten, decrease in the angle of a joint, pull against gravity |
| Eccentric | muscles lengthen with tension, increase in angle of a joint, works with gravity |
Created by:
BOkereke